Shock wave balloon catheter with multiple shock wave sources

ABSTRACT

An apparatus includes a balloon adapted to be placed adjacent a calcified region of a body. The balloon is inflatable with a liquid. The apparatus further includes a shock wave generator within the balloon that produces shock waves that propagate through the liquid for impinging upon the calcified region adjacent the balloon. The shock wave generator includes a plurality of shock wave sources distributed within the balloon.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application is a continuation of U.S. Ser. No. 15/474,885, filedMar. 30, 2017, which in turn is a continuation of U.S. Ser. No.13/534,658, filed Jun. 27, 2012, the disclosures of which areincorporated herein by reference in their entirety.

BACKGROUND OF THE INVENTION

Aortic calcification, also called aortic sclerosis, is a buildup ofcalcium deposits on the aortic valve in the heart. This often results ina heart murmur, which can easily be heard with a

stethoscope over the heart. However, aortic calcification usuallydoesn't significantly affect the function of the aortic valve.

In some cases, though, the calcium deposits thicken and cause narrowingat the opening of the aortic valve. This impairs blood flow through thevalve, causing chest pain or a heart attack. Doctors refer to suchnarrowing as aortic stenosis.

Aortic calcification typically affects older adults. But when it occursin younger adults, it's often associated with an aortic valve defectthat is present at birth (congenital) or with other illnesses such askidney failure. An ultrasound of the heart (echocardiogram) candetermine the severity of aortic calcification and also check for otherpossible causes of a heart murmur.

At present there is no specific treatment for aortic calcification.General treatment includes the monitoring for further developments ofheart disease. Cholesterol levels are also checked to determine the needfor medications to lower cholesterol in the hope to prevent progressionof aortic calcification. If the valve becomes severely narrowed, aorticvalve replacement surgery may be necessary.

The aortic valve area can be opened or enlarged with a balloon catheter(balloon valvuloplasty) which is introduced in much the same way as incardiac catheterization. With balloon valvuloplasty, the aortic valvearea typically increases slightly. Patients with critical aorticstenosis can therefore experience temporary improvement with thisprocedure. Unfortunately, most of these valves narrow over a six to 18month period. Therefore, balloon valvuloplasty is useful as a short-termmeasure to temporarily relieve symptoms in patients who are notcandidates for aortic valve replacement.

Patients who require urgent noncardiac surgery, such as a hipreplacement, may benefit from aortic valvuloplasty prior to surgery.Valvuloplasty improves heart function and the chances of survivingnon-cardiac surgery. Aortic valvuloplasty can also be useful as a bridgeto aortic valve replacement in the elderly patient with poorlyfunctioning ventricular muscle. Balloon valvuloplasty may temporarilyimprove ventricular muscle function, and thus improve surgical survival.Those who respond to valvuloplasty with improvement in ventricularfunction can be expected to benefit even more from aortic valvereplacement. Aortic valvuloplasty in these high risk elderly patientshas a similar mortality (5%) and serious complication rate (5%) asaortic valve replacement in surgical candidates.

Transarterial aortic valve replacement is a new procedure where theaortic valve is replaced with a self-expanding nitinol orballoon-expandable valve structure. Such procedures benefit from asmooth non-calcified circumference to attach the new valve. Largecalcium deposits may induce leaks around the valve preventing a firmconsistent attachment of the valve to the aorta. Thus there is a needfor a calcium free valve bed to attach such self-expanding valves.

An alternative method and system for treating stenotic or calcifiedaortic valves is disclosed and claimed in co-pending U.S. applicationSer. No. 12/611,997, filed Nov. 11, 2009 for SHOCKWAVE VALVULOPLASTYSYSTEM. As described therein, a balloon is placed adjacent leaflets of avalve to be treated and is inflatable with a liquid. Within the balloonis a shock wave generator that produces shock waves that propagatethrough the liquid and impinge upon the valve. The impinging shock wavessoften, break and/or loosen the calcified regions for removal ordisplacement to open the valve or enlarge the valve opening.

The approach mentioned above provides a more tolerable treatment foraortic stenosis and calcified aortic valves than the previouslyperformed aortic valve replacement. It is also a more effectivetreatment than current valvuloplasty therapy. For patients undergoingtransaortic or catheter based aortic valve replacement, this new methodcan soften, smooth, and open the aortic valve annulus more effectivelythan current valvuloplasty and prepare the area for a catheter deliveredvalve.

In the shock wave valvuloplasty described above, the impingementintensity of the shockwaves diminishes as a function of the distancefrom the shock wave origination point to the valve. More specifically,the impingement intensity of the shock waves is inversely proportionalto the square of the distance from the shock wave origination point tothe valve. Hence, when applying the shock waves, it would be desirableto maximize their effectiveness by being able to minimize the distancebetween the shock wave source and the valve location being treated atthat moment.

Similar issues are present in angioplasty. There, a calcified region ofa vein or artery may extend over some longitudinal distance of the veinor artery. A point shock wave source within an angioplasty balloon, insuch instances, would not be uniformly effective across the extent ofthe calcified region because of the varying distance from the shock wavesource to the various portions of the calcified region.

The present invention addresses this and other matters of importance inproviding the most efficient and effective valvuloplasty and angioplastytreatment possible.

SUMMARY OF THE INVENTION

In one embodiment, an apparatus comprises a balloon adapted to be placedadjacent a calcified region of a body. The balloon is inflatable with aliquid. The apparatus further includes a shock wave generator within theballoon that produces shock waves that propagate through the liquid forimpinging upon the calcified region adjacent the balloon. The shock wavegenerator includes a plurality of shock wave sources distributed withinthe balloon, wherein the plurality of shock wave sources are more thantwo shock wave sources. These shock wave sources can be distributed bothlongitudinally and circumferentially within the balloon for optimaleffect.

The balloon is elongated having a longitudinal dimension along itslength and the plurality of shock wave sources extend along a portion ofthe longitudinal dimension. The balloon has a sidewall and the shockwave sources are in non-touching relation with respect to the balloonsidewall. The shock wave generator may be an electrical arc shock wavegenerator and the shock wave sources may include a plurality ofelectrodes. The electrical arc shock wave generator may further includeat least one counter electrode adapted to be in contact with the liquidand to receive a voltage polarity opposite a voltage polarity applied tothe plurality of electrodes.

The shock wave generator may include an elongated conductor and aninsulator overlying the elongated conductor. The insulator may have aplurality of discrete openings, each opening for exposing the elongatedconductor to the fluid, to form the plurality of electrodes. Aninsulated wire may be employed to form the elongated conductor and theoverlying insulator.

The apparatus may further include an elongated carrier. The carrier mayextend through the balloon and be sealed thereto. The insulated wire maybe wrapped about the carrier within the balloon. The carrier may includea guide wire lumen. The insulated wire may be wrapped about the carrierto form electrode coil turns and the apparatus may further include aconductor wire wrapped about the carrier within the balloon and inbetween the electrode coil turns to form the counter electrode.

The shock wave generator may include an elongated cylindrical conductorand an insulator overlying the elongated cylindrical conductor. Theinsulator may have a plurality of discrete openings, each opening forexposing the elongated cylindrical conductor to the fluid, to form theplurality of electrodes. The apparatus may further include an elongatedcarrier extending through the balloon and be in sealed relation thereto.The elongated cylindrical conductor may overlie the carrier within theballoon. The elongated carrier may include a guide wire lumen.

The shock wave generator may be an electrical arc shock wave generator,wherein the shock wave sources include a plurality of electrodes,wherein the apparatus further includes an elongated carrier having alongitudinal dimension extending through the balloon and being in sealedrelation thereto, wherein the elongated carrier has a guide wire lumenextending along at least a portion of the longitudinal dimension of theelongated carrier, and wherein at least some of the plurality ofelectrodes are distributed along the elongated carrier within theballoon.

The elongated carrier may be formed of an insulating material. The shockwave generator may include at least one conductor extending within theelongated carrier in spaced apart relation to the guide wire lumen andalong at least a portion of the longitudinal dimension of the elongatedcarrier and a plurality of discrete portions of the elongated carrierinsulating material are removed to expose corresponding portions of theat least one conductor to form the at least some of the plurality ofelectrodes. At least some of the removed discrete portions of theelongated carrier insulating material may contain a conductive filling.The conductive fillings may be conductively secured to the elongatedconductor.

The elongated carrier may be formed of an insulating material. The shockwave generator may include at least first and second elongatedconductors extending within the elongated carrier in spaced apartrelation to each other and the guide wire lumen and along at least aportion of the longitudinal dimension of the elongated carrier. Aplurality of discrete portions of the elongated carrier insulatingmaterial may be removed to expose corresponding portions of the at leastfirst and second conductors to form the at least some of the pluralityof electrodes.

The removed discrete portions of the elongated carrier insulatingmaterial that expose corresponding portions of one of the at least firstand second conductors are greater in dimension than the removed discreteportions of the elongated carrier insulating material that exposecorresponding portions of another one of the at least first and secondconductors. The at least some of the removed discrete portions of theelongated carrier insulating material may contain a conductive fillingand at least some of the conductive fillings may be conductively securedto the elongated conductors.

The plurality of electrodes are arranged in series circuit relation.Alternatively the plurality of electrodes are arranged in parallelcircuit relation. The apparatus may further include a power source and amultiplexer that selectively couples the power source to the pluralityof electrodes, one at a time. In another embodiment, the plurality ofelectrodes may be arranged in a plurality of series circuit arrangementsand the apparatus may further include a multiplexer that selectivelycouples the power source to the series circuit arrangements, one at atime.

The plurality of shock wave sources may be arranged along a pathdefining a loop. The balloon may be configured to be placed adjacentleaflets of a valve, the balloon having a first chamber to be adjacentone side of the leaflets and a second chamber to be adjacent an oppositeside of the leaflets. The plurality of shock wave sources may bearranged to define a loop of shock wave sources within one of the firstand second chambers of the balloon.

The balloon may be configured to be placed adjacent leaflets of a valve,the balloon having a first chamber to be adjacent one side of theleaflets and a second chamber to be adjacent an opposite side of theleaflets, and wherein the plurality of shock wave sources may bearranged to define a first loop of shock wave sources within the firstchamber of the balloon and a second loop of shock wave sources withinthe second chamber of the balloon.

In accordance with another embodiment, an apparatus comprises anelongated carrier and a balloon carried on the elongated carrier insealed relation thereto. The balloon is adapted to be placed adjacent acalcified region of a body and is inflatable with a liquid. Theapparatus further includes an electrical arc shock wave generator withinthe balloon. The electrical arc shock wave generator includes more thantwo electrodes distributed within the balloon. Each electrode is adaptedto produce shock waves that propagate through the liquid for impingingupon the calcified region adjacent the balloon. The apparatus furtherincludes a counter electrode adapted to be in contact with the liquidand to receive a voltage polarity opposite that applied to the more thantwo electrodes.

In a further embodiment, a method includes the steps of inserting aballoon in a body adjacent a calcified region, inflating the balloonwith a liquid to cause the balloon to contact the calcified region,placing, within the balloon, a shock wave generator including more thantwo shock wave sources and distributing the more than two shock wavesources within the balloon, and causing the shock wave sources to formshock waves that propagate through the liquid and impinge upon thecalcified region.

The inserting step may include inserting the balloon into an artery orvein of the body. The balloon may be elongated having a longitudinaldimension and the distributing step may include distributing the shockwave sources along a portion of the longitudinal dimension.

The inserting step may include inserting the balloon into a valve of thebody. The distributing step may include distributing the shock wavesources along a path defining a loop.

The balloon may be configured to be placed adjacent leaflets of thevalve and to have a first chamber adapted to be adjacent one side of theleaflets and a second chamber adapted to be adjacent an opposite side ofthe leaflets. The inserting step may include inserting the balloon intothe valve with the first chamber adjacent one side of the leaflets andthe second chamber adjacent the opposite side of the leaflets. Thedistributing step may include distributing the shock wave sources alonga path defining a loop of shock wave sources within one of the first andsecond chambers of the balloon.

In a still further embodiment, the balloon is configured to be placedadjacent leaflets of the valve, wherein the balloon has a first chamberto be adjacent one side of the leaflets and a second chamber to beadjacent an opposite side of the leaflets, wherein the inserting stepincludes inserting the balloon into the valve with the first chamberadjacent one side of the leaflets and the second chamber adjacent theopposite side of the leaflets, and wherein the distributing stepincludes distributing the shock wave sources to define a first loop ofshock wave sources within the first chamber of the balloon and to definea second loop of shock wave sources within the second chamber of theballoon.

The balloon has a sidewall and the distributing step may includedistributing the shock wave sources in non-touching relation withrespect to the balloon sidewall. The shock wave generator may be anelectrical arc shock wave generator, the shock wave sources may includea plurality of electrodes, and the causing step may include applyingvoltage pulses between the plurality of electrodes and a counterelectrode to form the shock waves.

According to a still further embodiment, a method comprises inserting aballoon in a body adjacent a calcified region, inflating the balloonwith a liquid to cause the balloon to contact the calcified region,placing, within the balloon, more than two electrodes in non-touchingrelation to the balloon and adjacent the calcified regions, placing acounter electrode in contact with the liquid, and applying voltagepulses between the more than two electrodes and the counter electrode,wherein the voltage pulses have a first polarity applied to the two ormore electrodes and a second polarity applied to the counter electrodecausing the more than two electrodes to form shock waves that propagatethrough the liquid and impinge upon the calcified region.

BRIEF DESCRIPTION OF THE DRAWINGS

The features of the present invention which are believed to be novel areset forth with particularity in the appended claims. The variousdescribed embodiments of the invention, together with representativefeatures and advantages thereof, may best be understood by makingreference to the following description taken in conjunction with theaccompanying drawings, in the several figures of which like referencenumerals identify identical elements, and wherein:

FIG. 1 is a is a simplified drawing of an angioplasty system embodyingthe invention including a side view of a dilating angioplasty ballooncatheter including a plurality of shock wave sources according to oneembodiment;

FIG. 2 is a side view of the catheter of FIG. 1 showing an alternateelectrode structure that may be employed within the dilating angioplastyballoon catheter of FIG. 1;

FIG. 3 is a side view of the catheter of FIG. 1 showing still anotheralternate electrode structure that may be employed within the dilatingangioplasty balloon catheter of FIG. 1;

FIG. 4 is a partial sectional view illustrating alternative aspects ofthe electrode structure of FIG. 3 to provide the plurality of shock wavesources;

FIG. 5 is a side view of another dilating angioplasty balloon catheterincluding a plurality of shock wave sources according to a furtherembodiment of the invention;

FIG. 6 is a perspective view illustrating a manner in which an electrodestructure of the catheter of FIG. 5 may be produced to provide theplurality of shock wave sources according to an embodiment of theinvention;

FIG. 7 is another perspective view illustrating another aspect of theelectrode structure for the of FIG. 5 according to an embodiment of theinvention;

FIG. 8 is a simplified schematic diagram of a shock wave angioplastysystem embodying the invention wherein the shock wave source electrodesare arranged in parallel circuit;

FIG. 9 is a simplified side view of the left ventricle, aorta, andaortic valve of a heart with a valvuloplasty treatment catheterembodying the invention within the aortic valve of the heart;

FIG. 10 is a perspective view, to an enlarged scale, of the electrodestructure employed in the valvuloplasty catheter of FIG. 9;

FIG. 11 is another simplified side view of the left ventricle, aorta,and aortic valve of a heart with a dual chamber valvuloplasty treatmentcatheter embodying the invention within the aortic valve of the heart;

FIG. 12 is a partial side view, to an enlarged scale, of an angioplastycatheter with an electrode structure that may be employed in theembodiments herein wherein the electrodes are arranged in seriescircuit;

FIG. 13 is a simplified schematic diagram of a shock wave angioplastysystem embodying the invention wherein the shock wave source electrodesare arranged in series circuit;

FIG. 14 is a simplified schematic diagram of a shock wave angioplastysystem embodying the invention wherein the shock wave source electrodesare arranged in plural series circuits with each series circuit beingindividually activated;

FIG. 15 is a simplified drawing of another angioplasty system embodyingthe invention including a side view of a dilating angioplasty ballooncatheter including a plurality of shock wave sources that are selectablycoupled to a power source, one at a time, according to anotherembodiment; and

FIG. 16 is a timing diagram illustrating the manner in which theelectrodes of FIG. 15 may be selectably coupled to a power source.

DETAILED DESCRIPTION OF THE INVENTION

FIG. 1 shows an angioplasty system 10 embodying the invention includinga dilating angioplasty balloon catheter 20 including a plurality ofshock wave sources according to one embodiment of the invention. Thecatheter 20 includes an elongated carrier 21, and a dilating balloon 26formed about the carrier 21 in sealed relation thereto at a seal 23. Theballoon 26 forms an annular channel 27 about the carrier 21 throughwhich fluid, such as saline, may be admitted into the balloon to inflatethe balloon. The carrier 21 includes a guide wire lumen 29. The guidewire lumen is arranged to receive a guide wire that may be used todirect the catheter to a desired location to locate the balloon adjacenta region of an artery or vein or to treated.

Carried by the carrier 21 is an electrode structure 40. The electrodestructure 40 includes an insulated wire 42 wound about the carrier 21.Within the insulation of the insulated wire 42 are a plurality ofopenings 44 that expose corresponding discrete portions of the insulatedwire conductor to the saline within the balloon. Each opening 44 forms acorresponding shock wave source or electrode 46. As may be see in FIG.1, a plurality of more than two electrodes are formed in this manner andin non-touching relation to the sidewalls of the balloon 26.

The electrode structure 40 also includes a counter electrode 24. Thecounter electrode 24 is disposed in non-touching relation to thesidewalls of the balloon 26 and serves as a common electrode to cause anelectrical arc to occur between each of the electrodes 46 and the commonelectrode 24 when a suitable high voltage is applied between theelectrodes 46 and the counter electrode 24.

To that end, the electrodes 24 and 46 are attached to a source 30 ofhigh voltage pulses through a connector 32. The electrodes 24 and 46 areformed of metal, such as stainless steel or tungsten, and are placed acontrolled distance apart to allow a reproducible arc for a givenvoltage and current. The electrical arcs between electrode 24 andelectrodes 46 in the fluid are used to generate shock waves in thefluid. The variable high voltage pulse generator 30 is used to deliver astream of pulses across electrode 24 and electrodes 46 to create astream of shock waves within and along the longitudinal length 25 of theballoon 26 and within the artery being treated (not shown). Themagnitude of the shock waves can be controlled by controlling themagnitude of the pulsed voltage, the current, the duration andrepetition rate. The insulating nature of the balloon 26 protects thepatient from electrical shocks.

The balloon 26 may be filled with water or saline in order to gently fixthe balloon in the walls of the artery in the direct proximity with thecalcified lesion. The fluid may also contain an x-ray contrast to permitfluoroscopic viewing of the catheter during use. As previouslymentioned, the carrier 21 includes a lumen 29 through which a guidewire(not shown) may be inserted to guide the catheter into position. Oncethe catheter is positioned through use of the guide wire (not shown) andguide wire lumen 29, the physician or operator can start with low energyshock waves and increase the energy as needed to crack the calcifiedplaque. Such shockwaves will be conducted through the fluid, through theballoon, through the blood and vessel wall to the calcified lesion wherethe energy will break the hardened plaque without the application ofexcessive pressure by the balloon on the walls of the artery.

The voltage needed to produce the arcs will depend on the gap betweenthe electrodes and is generally 100 to 3000 volts. The pulse durationwill also depend on the surface area of the electrodes 24 and 46 andneeds to be sufficient to generate a gas bubble at the surface of theelectrodes to cause a plasma arc of electric current to jump each bubbleand, upon each occurrence, create a rapidly expanding and collapsingbubble, which creates the mechanical shock wave in the balloon. Suchshock waves can be as short as a few microseconds. Both the rapidexpansion and the collapse of a bubble create shock waves. The pulseduration can be adjusted to favor one over the other. A large steambubble will generate a stronger shockwave than a small one. However,more power is needed in the system to generate this large steam bubble.Traditional lithotripters try to generate a large steam bubble tomaximize the collapsing bubble's shockwave. Within a balloon such largesteam bubbles are less desirable due to the risk of balloon rupture. Byadjusting the pulse width to a narrow pulse less than two microsecondsor even less than one microsecond, a rapidly expanding steam bubble andshockwave can be generated while at the same time the final size of thesteam bubble can be minimized. The short pulse width also reduces theamount of heat in the balloon to improve tissue safety.

FIG. 2 shows another electrode structure 140 that may be employed in thecatheter 20 of FIG. 1. Like the electrode structure of FIG. 1, theelectrode structure 140 of FIG. 2 includes an insulated wire 142 woundabout the carrier 21 to form electrode coil turns 144. Within theinsulation of the insulated wire 142 are a plurality of openings 146that expose corresponding discrete portions of the insulated wireconductor to the saline within the balloon. Each opening 146 forms acorresponding shock wave source or electrode 148.

The electrode structure 140 further includes a conductor wire wrappedabout the carrier 21 within the balloon 26. The conductor wire 150 iswound in between the electrode coil turns 144 to form a counterelectrode 152. This provides more uniform spacings between theelectrodes 148 and the counter electrode 152. All of the electrodes 148and 152 are disposed in non-touching relation to the sidewalls of theballoon 26.

FIG. 3 shows another electrode structure 240 that may be employed in thecatheter 20 of FIG. 1. Here, the electrode structure 240 of the catheter20 includes an elongated cylindrical conductor 242 formed of metal, suchas stainless steel or tungsten, that overlies the carrier 21. Theelectrode structure 240 further includes an insulator 244 overlying theelongated cylindrical conductor 242. The insulator 244 has a pluralityof discrete openings 246 that expose corresponding areas of theelongated cylindrical conductor to the saline within the balloon 26.Each opening 246 forms a corresponding electrode 248. Another electrode250 forms a common electrode. All of the electrodes 248 and 250 aredisposed in non-touching relation to the sidewalls of the balloon 26.

FIG. 4 is a partial sectional view illustrating alternative aspects ofthe electrode structure 240 of FIG. 3 to provide the plurality of shockwave sources. Here, at least some of the openings 246 are filled with aconductive material to form the electrodes 249. The conductive fillerforming electrodes 249 may be of the same material forming theconductive cylinder 242 or may be of a different conductive material. Itserves to raise the surface of the electrodes to above the insulator 244which, in some cases, may result in more reliable arc formation.

Referring now to FIG. 5, it is a side view of another dilatingangioplasty balloon catheter 320 including a plurality of shock wavesources according to a further embodiment of the invention. Again, thecatheter 320 includes an elongated carrier 321 and an angioplastydilating balloon 326 at the distal end thereof in sealed relationthereto. The balloon 326 and carrier 321 form a channel 327 throughwhich the balloon may be filled with a liquid, such as water or saline.The carrier 321 also includes a guide wire lumen 329 that is adapted toreceive a guide wire 330.

The catheter 320 further includes an electrode structure 340 including afirst plurality of electrodes 332 and a second plurality of electrodes342. The electrodes 332 and 342 are disposed in non-touching relation tothe sidewalls of the balloon 326. During angioplasty treatment, avoltage having a first polarity is applied to the first plurality ofelectrodes 332 and a reversed polarity is applied to the secondplurality of electrodes 342. If the voltage across electrodes 332 and342 is applied as previously described, an arc will form betweencorresponding pairs of the electrodes 332 and 342 to producecorresponding shock waves. In this manner, shock waves are producedalong the longitudinal dimension of the balloon 326.

It may be seen in FIG. 5 that the electrodes 332 are of larger dimensionand have a greater surface area in contact with the saline in theballoon than the electrodes 342. This reduces the impedance to arcplasma formation, allowing the arc plasmas to be produced soon after thevoltage is applied to the electrodes. It has also been found that thiscauses larger arc plasmas to be formed producing stronger shock waves.It still further assists in controlling the electrodes across which theelectrical arcs will be produced.

FIG. 6 is a perspective view illustrating a manner in which an electrodestructure of the catheter of FIG. 5 may be produced to provide theplurality of shock wave sources according to an embodiment of theinvention. In FIG. 6 it may be seen that the electrode structure 340includes a first conductor 344 and a second conductor 346. Theconductors 344 and 346 extend along and within the carrier 321. Theconductors 344 and 346 may be made to extend along and within thecarrier 321 by co-extruding the conductors 344 and 346 with theelongated carrier during manufacture of the carrier 321. After theextrusion process, openings 348 and 350 may be formed in the carrier 321to expose corresponding portions of the conductors 344 and 346. Thisresults in the formation of electrodes 332 and 342 respectively. FIG. 7shows that the openings, such as opening 350 formed in the carrier 321may be filled with a conductive filler to form electrode 342.

FIG. 8 is a simplified schematic diagram of a shock wave angioplastysystem 410 embodying the invention wherein the shock wave sourceelectrodes are arranged in parallel circuit. For purposes of thisdescription, the catheter 320 of FIG. 5 shall be used for illustration.The system includes a high voltage generator 430, a connector 432, and acatheter 320. The catheter 320 includes the first plurality ofelectrodes 332 and a second plurality of electrodes 342. Each electrodeof the first plurality of electrodes 332 finds a corresponding electrodein the second plurality of electrodes 342. The connector 422 connectseach of the electrodes of the first plurality of electrodes 332 to theplus (+) side of the voltage generator 430 through a resistance R andeach of the electrodes of the second plurality of electrodes 342 to theminus (−) side of the voltage generator 430. The resistance R may beprovided through individual resistive elements or through resistivity inthe conductors that connect the electrodes to the connector and areprovided to equalize the current available to each electrode pair. Thisassures that no one electrode pair will sink all of the availablecurrent precluding all other electrode pairs from producing anelectrical arc.

FIG. 9 is a simplified side view of the left ventricle 500, aorta 502,and aortic valve 504 of a heart with a valvuloplasty treatment catheter510 embodying the invention within the aortic valve of the heart. Thecatheter 510 includes a treatment balloon 526 placed on both sides ofthe aortic valve leaflets 506. Valves of the heart, such as the aorticvalve 504 can become stenotic and calcified. More particularly, theopening of the valve defined by the leaflets can become stenotic andcalcified. This can restrict the size of the opening as the valveleaflets 506 are thickened with calcium deposits and fibrotic tissue.The thickened leaflets 506 and smaller valve opening restrict blood flowfrom the heart creating excess work for the heart and poor cardiacoutput. Current treatment includes replacement of the valve or attemptsto stretch the valve annulus with a balloon.

The treatment balloon 526 includes two longitudinally spaced chambers528 and 530 placed on opposed sides of the aortic valve leaflets 506.The balloon 526 may be formed from a compliant or a non-compliantmaterial. The balloon is at the distal end of a carrier 521. Thecatheter is placed into position by an elongated delivery tube 532.

The two longitudinally spaced chambers 530 and 528 share a commoninflation lumen 534 of the carrier 521 to permit the balloon 526 to befilled with a liquid, such as saline. Alternatively the balloon chambers530 and 528 may not share the same inflation fluid path.

The catheter 510 includes a plurality of shock wave sources that produceelectrical arcs within the balloon to produce shock waves within theconfined liquid. The shock waves propagate through the liquid andimpinge upon the balloon wall and the valve. The impinging shock wavescause the calcified material on the valve to break and/or soften. Thispermits the valve opening to be widened or the calcified material to beremoved.

In accordance with the embodiment of FIG. 9, the catheter 510 includesan electrode structure 540 within balloon chamber 528. The electrodestructure 540 may be seen in greater detail in FIG. 10. The electrodestructure generally includes a plurality of electrodes 542 distributedin a path defining a loop and a common or counter electrode 544. Theplurality of electrodes may be formed in a manner as previouslydescribed by use of an insulated conductor, such as an insulated wirewith discrete portion of the insulation removed to form the electrodes.Each of the electrodes 542 forms a shock wave source. As may be seen inFIG. 9, the electrodes 542 are arranged to be in non-touching relationto the sidewalls of the balloon 526.

In use, one polarity, as for example the positive polarity, of the arcforming voltage may be applied to the plurality of electrodes 542. Theminus polarity may be applied to the counter electrode 544. Because theelectrodes 542 are distributed along the loop as shown, the spacingbetween the electrodes and the valve will remain essentially constant toenable the entire aortic valve to be treated without diminished shockwave intensities.

FIG. 11 is another simplified side view of the left ventricle 500, aorta502, and aortic valve 504 of a heart with another valvuloplastytreatment catheter 610 embodying the invention within the aortic valveof the heart. The catheter 610 includes a treatment balloon 626 placedon both sides of the aortic valve leaflets 506. The treatment balloon626 includes two longitudinally spaced chambers 628 and 630 placed onopposite sides of the aortic valve leaflets 506. The balloon 626 may beformed from a compliant or a non-compliant material. The balloon is atthe distal end of a carrier 621. The catheter is placed into position byan elongated delivery tube 632.

The two longitudinally spaced chambers 630 and 628 share a commoninflation lumen 634 of the carrier 621 to permit the balloon 626 to befilled with a liquid, such as saline. Alternatively the balloon chambers630 and 628 may not share the same inflation fluid path.

Each of the balloon chambers 628 and 630 of the catheter 610 includes aplurality of shock wave sources that produce electrical arcs withintheir respective chambers of the balloon to produce shock waves withinthe confined liquid. The shock waves propagate through the liquid andimpinge upon the balloon wall and the valve. The impinging shock wavescause the calcified material on the valve to break and/or soften. Thispermits the valve opening to be widened or the calcified material to beremoved.

In accordance with the embodiment of FIG. 11, the catheter 610 includesan electrode structure 640A and 640B within balloon chambers 628 and630, respectively. The electrode structures may take the form ofelectrode structure 540 as shown in FIG. 10. Because the electrodes aredistributed in each balloon chamber 628 and 630 along a loop as shown,the spacing between the electrodes and the valve on each side of thevalve will remain essentially constant to enable both sides of theentire aortic valve to be treated without diminished shock waveintensities.

FIG. 12 is a partial side view, to an enlarged scale, of an angioplastycatheter with an electrode structure that may be employed in theembodiments herein, wherein the electrodes are arranged in seriescircuit. The catheter 710 may be seen to include an angioplasty balloon726 that is carried at the distal end of an elongated insulative carrier721 in sealed relation thereto. As in previous embodiments, the carrierhas a guide wire lumen 729.

Embedded within the carrier 721 is a conductor 740 that extends to thedistal end of the carrier and then back toward the proximal end asshown. At points along the carrier 721 and the conductor 740, portionsof the carrier 721 are removed. Corresponding portions of the conductorare also removed. Each removed conductor portion forms a pair ofelectrodes. For example, removed portion 742 forms an electrode pair743. Similarly, removed portions 744 and 746 form electrode pairs 745and 747 respectively. One side of the openings 742, 744, and 746 arecoated with a conductive material to render one electrode 743 a, 745 a,and 747 a of each electrode pair larger in surface area then the itsother corresponding electrode.

Each of the electrode pairs 743, 745, and 747 forms a shock wave source.As may be noted in FIG. 13, the electrode pairs 743, 745, and 747 arearranged in series circuit. They are connected to a high voltage source730 through a connector 732. The larger electrode 743 a, 745 a, and 747a of each electrode pair assures that all of the electrode pairs willreliably arc when the high voltage is applied across the string of shockwave sources.

FIG. 14 is a simplified schematic diagram of a shock wave angioplastysystem 800 embodying the invention wherein the shock wave sourceelectrodes are arranged in plural series circuits with each seriescircuit being individually activated. To that end, the system 800includes series circuits 802, 804, and 806 of electrode pairs connectedto a multiplexer 734 through a connector 732. The multiplexer isarranged to connect a high voltage source 730 across each series circuit802, 804, and 806 individually, one at a time, or in any combination.

FIG. 15 is a simplified drawing of another angioplasty system 900embodying the invention including a side view of a dilating angioplastyballoon catheter 910 including a plurality of shock wave sources thatare selectably coupled to a power source, one at a time, according toanother embodiment, and FIG. 16 is a timing diagram illustrating themanner in which the electrodes of FIG. 15 may be selectably coupled to apower source. The system 900 includes a catheter 920, and high voltagepower source 930, and a connector 934. The catheter 920 includes anangioplasty balloon 926 carried on a carrier 921 in sealed relationthereto and arranged to be inflated by a liquid, such as saline. Thecatheter 920 also includes electrodes 940, 942, and 944 carried on thecarrier 921 in non-touching relation to the sidewalls of the balloon926, and a counter electrode 946, also carried on the carrier 921. Theelectrodes 940, 942, and 944 are each connected to a multiplexer 934 ofthe high voltage source 930. When an electrode is activated, a highvoltage from source 930 is applied across a selected one of theelectrodes and the counter electrode to create an electrical arc. Theelectrical arc causes a plasma to be formed. The creation of the plasmacauses a shock wave. Hence, each electrode 940, 942, and 944 forms ashock wave source. The shock waves are propagated through the liquid toimpinge upon the balloon sidewall and the calcium deposit to break thecalcium deposit up.

As may be seen in FIG. 16, the multiplexer 934 can activate the shockwave sources, one at a time. This reserves all of the high voltage foreach shock wave source to thus form shock waves of maximum strength tobe applied to the calcium deposits all along the balloon. The shockwaves can be of repeatable strength. Longitudinal movement of thecatheter to treat the calcium deposits is not required.

While particular embodiments of the present invention have been shownand described, modifications may be made, and it is therefore intendedto cover all such changes and modifications which fall within the truespirit and scope of the invention.

We claim:
 1. A device for generating shock waves for treating acalcified lesion within a blood vessel or calcified aortic valvecomprising: an elongated support; a fluid fillable chamber mounted onthe support; a first wire extending along the support and into thechamber, wherein the distal end of the first wire defines a firstelectrode of a first pair of electrodes, there being at least two pairsof electrodes extending along support and wherein a second wire extendsalong the support and into the chamber, wherein the distal end of thesecond wire defines the second electrode in the most distal of theelectrode pairs, and wherein one electrode in each pair has a surfacearea greater than the surface area of the other electrode in the pair,with the electrode pairs being arranged such that when a high voltagepulse is applied to the proximal ends of the first and second wires,arcs are generated in the fluid adjacent each electrode pair whereby aseries connection is defined between the first and second wires and theintermediate electrode pairs, with a shock wave being generated fromeach electrode pair.
 2. The device of claim 1 further including aconductive element, with one portion of the conductive element defininga second electrode of the first pair and another portion of theconductive element defining a first electrode in a second pair ofelectrodes.
 3. The device of claim 2 wherein the conductive element is awire.
 4. The device of claim 2 wherein there is at least one additionalelectrode pair between the first pair of electrodes and the most distalpair of electrodes.
 5. The device of 4 wherein the elongated supportincludes a guide wire lumen.
 6. The device of claim 4 wherein thechamber is in the form of an inflatable balloon.
 7. The device of 1wherein the elongated support includes a guide wire lumen.
 8. The deviceof claim 1 wherein the chamber is in the form of an inflatable balloon.9. A device for generating shock waves for treating a calcified lesionwithin a blood vessel or calcified aortic valve comprising: an elongatedsupport; a fluid fillable chamber mounted on the support; a first wireextending along the support and into the chamber, wherein the distal endof the first wire defines a first electrode of a first pair ofelectrodes, there being at least two pairs of electrodes extending alongsupport and wherein a second wire extends along the support and into thechamber, wherein the distal end of the second wire defines the secondelectrode in a second pair of electrodes, and wherein one electrode ineach pair has a surface area greater than the surface area of the otherelectrode in the pair, with the electrode pairs being arranged such thatwhen a high voltage pulse is applied to the proximal ends of the firstand second wires, arcs are generated in the fluid adjacent eachelectrode pair whereby a series connection is defined between the firstand second wires and the intermediate electrode pairs, with a shock wavebeing generated from each electrode pair.
 10. The device of claim 9further including a conductive element, with one portion of theconductive element defining a second electrode of the first pair andanother portion of the conductive element defining a first electrode inthe second pair of electrodes.
 11. The device of claim 10 wherein theconductive element is a wire.
 12. The device of claim 9 wherein there isat least one additional electrode pair connected in series between thefirst and second wires.
 13. The device of 12 wherein the elongatedsupport includes a guide wire lumen.
 14. The device of claim 12 whereinthe chamber is in the form of an inflatable balloon.
 15. The device of 9wherein the elongated support includes a guide wire lumen.
 16. Thedevice of claim 9 wherein the chamber is in the form of an inflatableballoon.